Phase-split glass and method for producing same

Abstract

Provided is a phase-split glass having a three-dimensional shape and excellent appearance after post-processing.　The phase-split glass has a first surface and a second surface provided facing each other, wherein at least one among the first surface and the second surface has a curved surface part, and the average aspect ratio of phase-split particles is 0.600 or more in each of five regions set at equal intervals along the plate thickness direction in a plate-thickness-direction cross section. Here, the aspect ratio is a ratio of the minor axis to the major axis of the phase-split particles.

Description

Phase-dividing glass and method for manufacturing the same

[0001] The present invention relates to phase-splitting glass and a method for manufacturing the same.

[0002] Phase-separated glass is glass that has been separated into at least two phases, obtained by utilizing the phase separation phenomenon, and is also called white glass. Patent Document 1 describes "molten glass composition being molded using a mold and plunger in a one-press method and slowly cooled to obtain a white glass container having a three-layer structure derived from the phase separation phenomenon of the glass composition in part or all of the neck and body" (

[0020] ).

[0003] International Publication No. 2016 / 021569

[0004] The present inventors obtained a phase-separated glass having a three-dimensional shape (at least one of two opposing surfaces having a curved portion) in accordance with the method described in Patent Document 1. Subsequently, in order to further achieve the desired shape, a post-processing was performed by grinding a portion of the obtained phase-separated glass to expose the cross-section. As a result, a yellowish tint sometimes appeared in the cross-section formed by the post-processing. In this case, the appearance of the phase-separated glass after post-processing is not good, and there is room for improvement.

[0005] This invention has been made in view of the above points, and aims to provide phase-splitting glass having a three-dimensional shape that has excellent appearance after post-processing.

[0006] As a result of diligent research, the inventors have found that the above objective can be achieved by adopting the following configuration, and have completed the present invention. That is, the present invention provides the following [1] to

[12] . [1] A phase-splitting glass having a first surface and a second surface provided opposite to each other, at least one of the first surface and the second surface having a curved portion, and in any of the five regions set at equal intervals along the thickness direction in the cross section in the thickness direction of the plate, the average aspect ratio of the phase-splitting particles is 0.600 or more. However, the aspect ratio is the ratio of the minor axis to the major axis of the phase-splitting particles. [2] The phase-splitting glass according to [1], wherein the difference between the maximum value and the minimum value of the average aspect ratio is 0.700 or less. [3] A phase-splitting glass having a first surface and a second surface provided opposite to each other, wherein at least one of the first surface and the second surface has a curved portion, and in any of the five regions set at equal intervals along the thickness direction in the cross section in the thickness direction of the plate, the average major axis of the phase-splitting particles is 1,000 μm or less. [4] The phase-splitting glass according to [3], wherein the difference between the maximum and minimum values ​​of the average major axis is 0,800 μm or less. [5] The phase-splitting glass according to any one of [1] to [4], wherein the average particle diameter of the phase-splitting particles is 0,200 μm or more and 2,000 μm or less. [6] The phase-splitting glass according to any one of [1] to [5], wherein the transmittance for light with a wavelength of 300 to 900 nm in a flat plate portion with a plate thickness of 0.78 mm is less than 1%. [7] The phase-splitting glass according to any one of [1] to [6], wherein the whiteness L* value of the first surface is 97 or more. [8] The phase splitting glass according to any one of [1] to [7], wherein the first surface has a convex portion, the second surface has a concave portion, and the surface roughness of the first surface is less than the surface roughness of the second surface. [9] The phase splitting glass according to [8], wherein the arithmetic mean height Sa of the first surface is 0.7 μm or less.

[10] The phase splitting glass according to any one of [1] to [9], wherein the haze is 95% or more.

[11] The phase splitting glass according to any one of [1] to

[10] , wherein the gloss is 96 or more and 110 or less.

[12] A method for manufacturing the phase-separated glass according to any one of [1] to

[11] above, comprising heating and melting glass raw materials to obtain molten glass, forming the phase-separated molten glass to obtain a flat glass mother board, and performing reheat forming by heating and press-forming the glass mother board. A method for manufacturing phase-separated glass.

[0007] According to the present invention, it is possible to provide a phase-separated glass having a three-dimensional shape and excellent appearance after post-processing.

[0008] It is a cross-sectional view showing a phase-separated glass. It is a schematic view showing a separated glass phase. It is a schematic view showing a part of the cross-section in the plate thickness direction of the phase-separated glass enlarged. It is a cross-sectional view showing a glass mother board. It is a cross-sectional view showing a molding die and a heater.

[0009] The meanings of the terms in the present invention are as follows. A numerical range represented by "~" means a range including the numerical values described before and after "~" as the lower limit value and the upper limit value.

[0010] [Phase-separated glass] FIG. 1 is a cross-sectional view showing a phase-separated glass 11. As shown in FIG. 1, the phase-separated glass 11 has a first surface 1 and a second surface 2 provided facing each other.

[0011] The phase-separated glass 11 does not have a flat shape but has a three-dimensional shape. That is, as shown in FIG. 1, at least one of the first surface 1 and the second surface 2 of the phase-separated glass 11 has a curved surface portion 3. In the phase-separated glass 11 shown in FIG. 1, both the first surface 1 and the second surface 2 have a curved surface portion 3. More specifically, the curved surface portion 3 of the first surface 1 is a convex surface portion 3a, and the curved surface portion 3 of the second surface 2 is a concave surface portion 3b.

[0012] <Phase-separated particles> FIG. 2 is a schematic view showing a separated glass phase. In the phase-separated glass 11, its glass phase is separated (phase-separated) into two or more glass phases. More specifically, as shown in FIG. 2, in the phase-separated glass 11, at least one glass phase exists dispersed as phase-separated particles 4a in another glass phase, which is a matrix phase 4b. ,

[0013] Figure 3 is a schematic diagram showing an enlarged portion of the cross-section of the phase-splitting glass 11 in the thickness direction. First, as shown in Figure 3, five virtual regions (referred to as region A1, region A2, region A3, region A4, and region A5, respectively) are set in the cross-section of the phase-splitting glass 11 in the thickness direction, along the thickness direction of the phase-splitting glass 11 (indicated by arrow 6). Details such as the size of each region (regions A1 to A5) will be described later.

[0014] The five regions (regions A1 to A5) can be set at any position in the in-plane direction of the phase-splitting glass 11 (the direction along the first surface 1 and the second surface 2) (for example, the position where the curved surface 3 is located).

[0015] 《Average Aspect Ratio》 In one embodiment of the present invention, the average aspect ratio of the phase-splitting particles is 0.600 or higher in all five regions. The aspect ratio is the ratio of the minor axis to the major axis of the phase-splitting particles (minor axis / major axis). Such a phase-splitting glass 11 suppresses the occurrence of yellowing in the cross-section formed by post-processing (processing to expose the cross-section by cutting a part of the phase-splitting glass 11), that is, it has an excellent appearance after post-processing. This is presumed to be because the distribution of the glass phase along the thickness direction of the phase-splitting glass 11 is uniform, thereby suppressing color heterogeneity.

[0016] For the reason that the appearance after post-processing is superior and a small surface roughness can be obtained, the average aspect ratio of the phase-divided particles is preferably 0.700 or higher, more preferably 0.800 or higher, even more preferably 0.900 or higher, and particularly preferably 0.933 or higher in any of the five regions. On the other hand, the average aspect ratio of the phase-divided particles may be 0.980 or lower, or 0.970 or lower in any of the five regions.

[0017] Furthermore, for reasons of achieving a superior appearance after post-processing and a smaller surface roughness, the difference between the maximum and minimum average aspect ratios is preferably 0.700 or less, more preferably 0.200 or less, even more preferably 0.060 or less, even more preferably 0.050 or less, and particularly preferably 0.040 or less.

[0018] 《Average Major Axis》 In another embodiment of the present invention, the average major axis of the phase-separated particles is 1.000 μm or less in any of the five regions. In this case as well, the appearance after post-processing is excellent. For the reason that the appearance after post-processing is even better and a small surface roughness can be obtained, the average major axis of the phase-separated particles is preferably 0.930 μm or less, more preferably 0.880 μm or less, even more preferably 0.830 μm or less, and particularly preferably 0.750 μm or less in any of the five regions. On the other hand, the average major axis of the phase-separated particles may be 0.500 μm or more, or 0.600 μm or more in any of the five regions.

[0019] Furthermore, for reasons of achieving a superior appearance after post-processing and a smaller surface roughness, the difference between the maximum and minimum values ​​of the average major axis is preferably 0.800 μm or less, more preferably 0.500 μm or less, even more preferably 0.300 μm or less, and particularly preferably 0.100 μm or less.

[0020] 《Average Particle Diameter》 In addition, in all five regions, the average particle diameter of the phase-separated particles is preferably 0.200 μm or more, more preferably 0.250 μm or more, and even more preferably 0.300 μm or more. On the other hand, in all five regions, the average particle diameter of the phase-separated particles is preferably 2.000 μm or less, more preferably 1.500 μm or less, and even more preferably 1.000 μm or less. The particle diameter is the equivalent circular diameter of the phase-separated particles.

[0021] 《Measurement Method》 The method for determining the aspect ratio, major axis, and particle size of the phase-separated particles is described in detail below.

[0022] (Sample preparation) First, a sample is prepared from the phase-splitting glass 11. Specifically, the phase-splitting glass 11 is cut with a glass cutter to expose the cross-section. Next, the exposed cross-section is mechanically polished. At this time, polishing is first performed using a grinding wheel with a grit size of #400, and then the grit size (grade) is changed in stages in the order of #600, #800, #1200, 3 μm abrasive grains and 1 μm abrasive grains. After that, a carbon vapor deposition layer with a thickness of 15 nm is formed on the polished surface (polished cross-section) of the sample.

[0023] (Acquisition of SEM images) Next, the polished surface of the sample is observed using a scanning electron microscope (SEM) under the following conditions, and an SEM image is obtained. • SEM: JSM-IT200LA (manufactured by JEOL Ltd.) • Acceleration voltage: 5kV • Observation mode: BED-C • Working distance (WD): 11mm • Magnification: 10k

[0024] (Image Processing) The obtained SEM image is processed using image processing software (ImageJ) according to the following procedure: 1) Correspond the length of the scale line in the SEM image to the number of pixels. 2) Cut out and remove the text information displayed at the bottom of the SEM image. 3) Perform smoothing on the SEM image from which the text information has been removed. 4) Binarize the smoothed SEM image to make the phase particles white. 5) In the binarized SEM image, separate overlapping phase particles. That is, to treat overlapping phase particles as separate phase particles, they are separated at the boundary. 6) Detect phase particles in each region (region A1 to region A5). The size of each region is 12.8 μm × 9.6 μm. For the two regions located at both ends (region A1 and region A5), the distance to the closer surface (second surface 2 or first surface 1) (distance D in Figure 3) is 1 / 6 of the plate thickness. Phase particles located at the edges of each region are excluded from detection. 7) For each region (regions A1 to A5), the particle diameter (equivalent circle diameter) of the detected phase particles is determined, and then the average value (average particle diameter) is calculated. 8) For each region (regions A1 to A5), the major axis and aspect ratio are determined for the top 10 phase particles in descending order of particle diameter, and then the average value (average major axis and average aspect ratio) is calculated. More specifically, image processing software (ImageJ) is used to fit the phase particles to an ellipse, and the major axis (length of the major axis) and minor axis (length of the minor axis) of the ellipse are determined (both in units of μm), and then the aspect ratio (minor axis / major axis) is calculated.

[0025] <Thickness> The thickness of the phase-splitting glass 11 depends on the application of the phase-splitting glass 11, but is, for example, 5.00 mm or less, preferably 3.00 mm or less, and more preferably 1.00 mm or less. There is no particular lower limit, and the thickness of the phase-splitting glass 11 is, for example, 0.30 mm or more, and may be 0.50 mm or more. The thickness is the distance between any point A on the first surface 1 and point B on the second surface 2, which is the shortest distance from point A, in the thickness-direction cross-section of the phase-splitting glass 11. The thickness is measured using a micrometer.

[0026] <Surface Roughness> In the phase splitting glass 11, it is preferable that the surface roughness of the first surface 1 having a convex portion 3a is smaller than the surface roughness of the second surface 2 having a concave portion 3b. This ensures that when the phase splitting glass 11 is used as a product housing, the first surface 1, which is the outer surface of the housing, has excellent appearance, while the second surface 2, which is the inner surface of the housing, has excellent adhesion to the product. Surface roughness can be expressed as the surface property parameter (Sa) specified in ISO 25178, which will be described below.

[0027] Surface property parameters are measured using a laser microscope. A field of view of 300 μm × 200 μm is set for the measurement surface of the sample (phase-splitting glass 11), the height information of the sample is measured, cutoff correction is performed, and the obtained height data is used. A cutoff value of 0.08 mm is used.

[0028] 《Sa》 The arithmetic mean height Sa of the first surface 1 is preferably 0.7 μm or less, more preferably 0.4 μm or less, and even more preferably 0.2 μm or less. The lower limit is not particularly limited, and the Sa of the first surface 1 may be, for example, 1.0 μm or more, and may be 2.0 μm or more. It is preferable that the Sa of the second surface 2 is greater than the Sa of the first surface 1.

[0029] <Transmittance> The phase-splitting glass 11 is preferably opaque so that light does not easily leak when used as a housing for a light-emitting product. Specifically, the phase-splitting glass 11 has a transmittance (hereinafter also simply referred to as "transmittance") of less than 5% for light with a wavelength of 300 to 900 nm in a flat plate portion with a plate thickness of 0.78 mm, preferably less than 3%, and more preferably less than 1%. The transmittance is measured using an ultraviolet-visible-near-infrared spectrophotometer.

[0030] <Whiteness> For aesthetic reasons, the phase-splitting glass 11 is preferably white. Specifically, the whiteness L* value of the first surface 1 of the phase-splitting glass 11 is preferably 93 or higher, more preferably 95 or higher, and even more preferably 97 or higher. The whiteness L* value is measured using a spectrophotometer.

[0031] <Haze> The haze of the phase-splitting glass 11 is preferably 85% or more, more preferably 90% or more, and even more preferably 95% or more. The upper limit is not particularly limited, but may be, for example, 100% or 98%. The haze is the transmitted haze as defined in JIS K 7136.

[0032] <Gloss> The gloss of the phase splitting glass 11 is preferably 85 or higher, more preferably 90 or higher, and even more preferably 96 or higher. On the other hand, the gloss of the phase splitting glass 11 is preferably 130 or lower, more preferably 120 or lower, and even more preferably 110 or lower. The gloss is the reflected gloss (gloss 60) incident at 60° as defined in JIS Z 8741:1997.

[0033] <Glass Composition> Next, an example of the composition (glass composition) of the phase-splitting glass 11 will be described. In the following description, unless otherwise specified, the "%" of the content of each component means "mol%" based on oxides. The content of unavoidable impurities is preferably 0.1% or less.

[0034] SiO ２ SiO is the basic component that forms the network structure of glass in phase-separated glass. That is, it adopts an amorphous structure and exhibits excellent mechanical strength, weather resistance, and gloss as glass. ２The content of [substance] is, for example, 50% or more, preferably 53% or more, more preferably 55% or more, and still more preferably 57% or more, because the weather resistance or scratch resistance as glass is improved. On the other hand, because the melting temperature of the glass should not become excessively high, the content of SiO ２ is, for example, 73% or less, preferably 70% or less, more preferably 68% or less, and still more preferably 65% or less.

[0035] B ２ O ３ is not an essential component, but it improves the melting property of the glass, improves the light shielding property of the glass, reduces the thermal expansion coefficient, and further improves the weather resistance. Therefore, the content of B ２ O ３ is, for example, 0.5% or more, preferably 1% or more, more preferably 2% or more, and still more preferably 3% or more. On the other hand, from the viewpoint of preventing unevenness in the whiteness of the glass, the content of B ２ O ３ is, for example, 10% or less, preferably 8% or less, more preferably 6% or less, and still more preferably 4% or less from the viewpoint of suppressing volatilization.

[0036] Na ２ O improves the melting property of the glass. Therefore, the content of Na ２ O is, for example, 3% or more, preferably 5% or more, more preferably 8% or more, and still more preferably 9% or more. When it is desired to increase the strength of the glass by ion exchange treatment, the content of Na ２ O is preferably 6% or more. On the other hand, from the viewpoint of preventing deterioration of the weather resistance and light shielding property of the glass, the content of Na ２ O is, for example, 17% or less, preferably 14% or less, more preferably 12% or less, still more preferably 11% or less, and particularly preferably 10% or less.

[0037] Nb ２ O ５ and Gd ２ O ３The content of at least one selected from the group consisting of the above is, for example, 0.5% or more, preferably 1% or more, more preferably 2% or more, and even more preferably 3% or more, because it sufficiently increases the refractive index difference of the two-phase separated glass and improves light shielding. On the other hand, from the viewpoint of preventing the glass from becoming brittle, this content is, for example, 10% or less, preferably 8% or less, more preferably 6% or less, and even more preferably 5% or less.

[0038] P ２ O ５ P is a basic component that significantly promotes the whitening of glass, and from the viewpoint of obtaining sufficient light-shielding properties, ２ O ５ The content of is, for example, 0.5% or more, preferably 2% or more, and more preferably 4% or more. On the other hand, from the viewpoint of suppressing volatilization and preventing the whiteness from becoming too uneven, P ２ O ５ The content is, for example, 10% or less, preferably 8% or less, and more preferably 7% or less.

[0039] MgO, CaO, SrO, and BaO are components that have the effect of greatly increasing light-shielding properties, and it is preferable to include at least one of them.

[0040] MgO is not essential, but SiO ２ and Na ２ In combination with O, it promotes phase separation and improves light shielding properties. For this reason, when MgO is included, its content is preferably more than 0.5%, more preferably 3% or more, even more preferably 5% or more, and particularly preferably 7% or more. On the other hand, the MgO content is preferably 18% or less, more preferably 11% or less, even more preferably 10% or less, and particularly preferably 9% or less.

[0041] If CaO is present, its content is preferably 1% or more, and more preferably 2% or more. On the other hand, from the viewpoint of preventing devitrification, the CaO content is preferably 7% or less, more preferably 6% or less, and even more preferably 5% or less.

[0042] If SrO is present, its content is preferably 1% or more, and more preferably 2% or more. On the other hand, from the viewpoint of preventing devitrification, the SrO content is preferably 10% or less, and more preferably 8% or less.

[0043] BaO has a greater effect on promoting light shielding than other alkaline earth metal oxides. When BaO is included, its content is preferably 1% or more, more preferably 3% or more, and even more preferably 5% or more. On the other hand, from the viewpoint of preventing devitrification, the BaO content is preferably 12% or less, more preferably 10% or less, and even more preferably 9% or less. Furthermore, from the viewpoint of suppressing scratching, the BaO content is preferably 8% or less, more preferably 5% or less, and even more preferably 2% or less.

[0044] From the viewpoint of preventing the melting temperature from rising, the total RO content of MgO, CaO, SrO, and BaO should be, for example, 2% or more, preferably 4% or more, more preferably 6% or more, and even more preferably 8% or more. On the other hand, from the viewpoint of suppressing devitrification, the RO should be, for example, 25% or less, preferably 20% or less, more preferably 16% or less, and even more preferably 12% or less.

[0045] Al ２ O ３ This improves the chemical durability of glass, and also SiO ２ This significantly improves the dispersion stability with other components and makes the phase separation of the glass uniform. Therefore, Al ２ O ３ The content of is preferably 1% or more, more preferably 2% or more, and even more preferably 3% or more. Furthermore, if it is desired to improve the chemical strengthening properties by ion exchange, 3% or more is preferred, and more preferably 4% or more. On the other hand, from the viewpoint of preventing the melting temperature of the glass from rising and preventing a decrease in light shielding properties, Al ２ O ３ The content is preferably 8% or less, more preferably 7% or less, even more preferably 6% or less, particularly preferably 5% or less, and most preferably 4% or less.

[0046] ZrO ２ While not essential, it may be included to improve chemical durability, etc. ZrO２ If it contains, the content is, for example, 0.5% or more. On the other hand, from the viewpoint of preventing a decrease in light shielding properties, ZrO ２ The content is preferably 5% or less, more preferably 4% or less, and even more preferably 3% or less.

[0047] TiO ２ It is not essential, but may be included to increase Young's modulus. TiO ２ If it contains, the content is, for example, 0.5% or more. On the other hand, from the viewpoint of preventing the devitrification temperature from rising, TiO ２ The content is preferably 5% or less, and more preferably 3% or less.

[0048] K ２ O is not essential, but may be included to increase the thickness of the compressive stress layer (DOL) due to ion exchange treatment. ２ If O is present, its content is, for example, 0.5% or more. On the other hand, from the viewpoint of preventing the surface compressive stress (CS) generated by ion exchange treatment from decreasing, K ２ The O content is preferably 5% or less, and more preferably 3% or less.

[0049] Li ２ O is not essential, but may be included to increase Young's modulus. Li ２ If O is present, its content is, for example, 0.5% or more. On the other hand, from the viewpoint of preventing the devitrification temperature from rising, Li ２ The O content is preferably 5% or less, and more preferably 3% or less.

[0050] The phase-splitting glass may contain components other than those described above (other components) to the extent that it does not impair the purpose of the present invention. The total content of other components is preferably 10% or less. ２ , B ２ O ３ Na ２ O, Nb ２ O ５ , Gd ２ O ３ , P ２ O ５ , MgO, CaO, SrO, BaO, Al２ O ３ and ZrO ２ The total content of the 12 components is preferably 90% or more, and may be 94% or more.

[0051] <Applications> Phase-splitting glass 11 is suitable for use in product casings, tableware, exterior materials, etc., due to its excellent appearance after post-processing.

[0052] [Method for manufacturing phase-splitting glass] Next, an example of a method for manufacturing phase-splitting glass 11 will be described.

[0053] <Preparation of glass matrix> Figure 4 is a cross-sectional view showing the glass matrix 21. The glass matrix 21 is prepared using glass raw materials as described below. The glass matrix 21 is a flat plate-shaped phase-splitting glass which is the base material for the phase-splitting glass 11.

[0054] 《Melting》 First, the glass raw material is heated and melted to obtain molten glass. The glass raw material is not particularly limited, and conventionally known glass raw materials can be used. The glass raw material is weighed so that it has the glass composition of the phase-separated glass 11 described above. The temperature at which the glass raw material is heated and melted (melting temperature) is set considering, for example, the phase separation start temperature described later, and is preferably above the phase separation start temperature. Setting the melting temperature above the phase separation start temperature suppresses heterogeneity in shielding degree (whiteness) due to the temperature distribution in the melting furnace. Specifically, the melting temperature is, for example, 1400 to 1750°C, and may also be 1600 to 1700°C. The time for heating and melting the glass raw material (melting time) is not particularly limited, and may be, for example, 1 to 50 hours, and may also be 2 to 24 hours. After melting the glass raw material, it may be homogenized by degassing, stirring, etc. Homogenization may be performed when separating the phases of the molten glass (described later).

[0055] Phase Splitting Process Next, a phase splitting process (phase splitting process) may be performed on the obtained molten glass. Phase splitting of glass (molten glass) refers to the separation of a single glass phase into two or more glass phases. Phase splitting is a process of holding the molten glass at the phase splitting temperature described later. Note that "holding (the molten glass) at the phase splitting temperature" includes not only holding the molten glass at a certain temperature included in the phase splitting temperature range, but also cooling the molten glass within the temperature range included in the phase splitting temperature range.

[0056] The phase splitting temperature is preferably below the phase splitting start temperature, more preferably 1500°C or below, even more preferably 1400°C or below, particularly preferably 1350°C or below, and most preferably 1325°C or below. Furthermore, the phase splitting temperature is preferably above 1200°C, more preferably 1225°C or above, even more preferably 1250°C or above, particularly preferably 1275°C or above, and most preferably 1300°C or above.

[0057] The time required for the phase separation process (phase separation process time) is preferably 1 minute or more, more preferably 5 minutes or more, and even more preferably 8 minutes or more. Furthermore, the phase separation process time is preferably 360 minutes or less, more preferably 240 minutes or less, even more preferably 120 minutes or less, and particularly preferably 90 minutes or less.

[0058] The viscosity of the molten glass at the phase separation temperature is set to 10 for the reason that it is easy to mold after phase separation. ６ Preferably dPa·s or less, 10 ５ dPa·s or less is more preferable, 10 ４ More preferably dPa·s or less, 10 ３．５ dPa·s or less is particularly preferred, 10 ３ A viscosity of dPa·s or less is most preferable. Furthermore, the viscosity of the molten glass at the phase splitting temperature is 10 because it helps to suppress non-uniformity of whiteness. ２ Preferably dPa·s or higher, 10 ２．５ More preferably dPa·s or higher, 10 ２．７ A value of dPa·s or higher is particularly preferred.

[0059] The phase splitting start temperature is measured using, for example, a hot-thermocouple device manufactured by Texcel. The hot-thermocouple device is a device that has a temperature detection function using a thermocouple, a heater function, and a sample holding function (see Japanese Patent Publication No. 2007-178412, Japanese Patent Publication No. 2011-059089, etc.). In general terms, the glass raw material is heated and melted, and the resulting molten glass is cooled at 1°C / s while being observed with an optical microscope, and the temperature at which condensation occurs in the molten glass is defined as the "phase splitting start temperature".

[0060] Depending on the glass composition, molten glass can be separated into phases without phase separation treatment. In other words, phase-separated molten glass can be obtained. In this case, the plate-shaping process described later can be carried out without phase separation treatment.

[0061] 《Plate Forming》 Next, the phase-separated molten glass is formed into a flat plate. At this time, known methods such as the float method and the down-draw method may be used. This yields a glass matrix 21 which is a flat plate of phase-separated glass.

[0062] <Reheat Molding> Next, the glass matrix 21 is subjected to reheat molding. More specifically, the glass matrix 21 is heated, and an external force is applied to the heated glass matrix 21 to form a curved portion 3 (see Figure 1) on the glass matrix 21, thereby obtaining phase-separated glass 11. In reheat molding, it is preferable to carry out heating and press molding in a batch process. This allows for precise control of the molding temperature for each shot, resulting in high shape accuracy.

[0063] Figure 5 is a cross-sectional view showing the mold 51 and heater 55. For reheat molding, a molding apparatus is used that has, for example, a mold 51 consisting of an upper mold 52 and a lower mold 53, and a heater 55 arranged around the mold 51.

[0064] The molding surface 52a of the upper mold 52 is a convex curved surface corresponding to the second surface 2 (see Figure 1) of the phase-splitting glass 11. The molding surface 53a of the lower mold 53 is a concave curved surface corresponding to the first surface 1 (see Figure 1) of the phase-splitting glass 11. The upper mold 52 and the lower mold 53 can be moved relative to each other in directions toward and toward each other by a drive source such as a motor (not shown).

[0065] The heater 55 heats the glass matrix 21 together with the mold 51 by radiant heating. The heater 55 is, for example, an infrared lamp heater, and various known heaters such as carbon lamps and halogen lamps can be used. Multiple heaters 55 are arranged along the height direction of the mold 51 in order to heat the mold 51 uniformly.

[0066] <Heating> First, the glass matrix 21 is heated by the heater 55 to a preset temperature (reheat temperature). More specifically, first, the upper mold 52 and the lower mold 53 are moved relative to each other in a direction away from each other. Next, with the glass matrix 21 placed on the lower mold 53, the glass matrix 21 is heated together with the molding die 51 by radiant heating from the heater 55 arranged around the molding die 51.

[0067] When heating the glass matrix 21 to the reheat temperature, a low heating rate is preferable. This makes it easier to obtain the aspect ratio and major axis of the phase-separated particles of the manufactured phase-separated glass 11. Specifically, the heating rate is, for example, 150.0°C / min or less, preferably 120.0°C / min or less, more preferably 90.0°C / min or less, even more preferably 60.0°C / min or less, even more preferably 45.0°C / min or less, particularly preferably 40.0°C / min or less, and very preferably 35.0°C / min or less. Most preferably 30.0°C / min or less.

[0068] On the other hand, the heating rate may be, for example, 3.0°C / min or more, 5.0°C / min or more, or 10.0°C / min or more.

[0069] The reheat temperature is preferably a temperature at which the glass matrix 21 does not melt (a temperature at which the glass matrix 21 does not soften), and specifically, for example, a temperature below the softening point is preferred. This makes it easier to obtain the above-mentioned aspect ratio and major axis for the phase-separated particles of the phase-separated glass 11 that is manufactured. Specifically, the reheat temperature depends on the glass composition, but for example, it is 950°C or lower, preferably 900°C or lower, more preferably 850°C or lower, even more preferably 800°C or lower, and particularly preferably 750°C or lower.

[0070] On the other hand, from the viewpoint of ease of molding, the reheat temperature is, for example, 500°C or higher, preferably 550°C or higher, more preferably 600°C or higher, even more preferably 650°C or higher, and particularly preferably 700°C or higher.

[0071] The viscosity of the glass matrix 21 heated to the reheat temperature (the glass matrix 21 when press molding is performed, as described later) is preferably 6.00 dPa·s or higher, more preferably 7.00 dPa·s or higher, even more preferably 8.00 dPa·s or higher, particularly preferably 9.00 dPa·s or higher, and most preferably 10.00 dPa·s or higher. On the other hand, from the viewpoint of ease of molding, this viscosity may be, for example, 14.50 dPa·s or lower, 14.00 dPa·s or lower, or 13.50 dPa·s or lower. This viscosity is measured using differential thermal analysis (DTA).

[0072] A temperature sensor (not shown) monitors the temperatures of the mold 51 and the glass matrix 21, and when the temperature of the glass matrix 21 reaches a preset reheat temperature, heating is stopped. When heating is stopped, the temperature difference between the upper mold 52 and the lower mold 53 is preferably 60°C or less, more preferably 55°C or less, and even more preferably 50°C or less.

[0073] Press forming Next, press forming is performed on the heated glass matrix 21. That is, the heated glass matrix 21 is pressed by the molding die 51. More specifically, the upper die 52 and the lower die 53 are moved relative to each other in a direction that brings them closer together, and the heated glass matrix 21, which is positioned between the upper die 52 and the lower die 53, is pressed.

[0074] For example, the convex molding surface 52a of the upper mold 52 presses downward on the glass matrix 21, deforming the glass matrix 21 and bringing the molding surface 52a of the upper mold 52 and the molding surface 53a of the lower mold 53 into close contact with both surfaces of the glass matrix 21. In this way, the curved shape of the molding surface 52a of the upper mold 52 is transferred to one surface of the glass matrix 21, forming the first surface 1. Also, the curved shape of the molding surface 53a of the lower mold 53 is transferred to the other surface of the glass matrix 21, forming the second surface 2. The molding surfaces 52a and 53a are brought close together to a distance corresponding to the thickness of the phase-splitting glass 11. This results in a phase-splitting glass 11 having the aforementioned thickness.

[0075] The load (press load) applied when pressing the heated glass matrix 21 is preferably 0.2 kN or more, and more preferably 0.4 kN or more. On the other hand, the press load may be, for example, 1.5 kN or less, or 1.0 kN or less.

[0076] The time for applying pressure to the glass matrix 21 heated by the aforementioned press load (press time) is preferably 20 seconds or more, and more preferably 40 seconds or more. On the other hand, the press time may be, for example, 100 seconds or less, or 80 seconds or less.

[0077] During press molding, nitrogen gas may be blown in through holes (not shown) provided in the mold 51 to ensure uniform molding.

[0078] After pressurizing the glass matrix 21 and allowing it to cool slowly as needed, the upper mold 52 and the lower mold 53 are moved relative to each other in a direction away from each other. Then, the glass matrix 21 is cooled. In this way, a press-formed glass matrix 21, i.e., phase-separated glass 11, is obtained.

[0079] The present invention will be specifically described below with reference to examples. However, the present invention is not limited to the examples described below. Examples 1 and 2 are examples, and Example 3 is a comparative example.

[0080] <Example 1> First, glass raw materials were prepared by weighing them to achieve the following glass composition 1.

[0081] Glass composition: • Glass composition 1: SiO ２: 59.6%, Al ２ O ３ : 5.4%, P ２ O ５ : 6.1%, B ２ O ３ : 3.9%, Na ２ O: 9.3%, ZrO ２ : 2.5%, MgO: 3.6%, BaO: 5.6%, Nb ２ O ５ : 4.0%

[0082] 《Preparation of glass matrix: melting and plate shaping》 Next, the prepared glass raw materials were heated in a furnace at 1660°C for 3 hours to melt them and obtain molten glass. The obtained molten glass was in phase. Subsequently, the phase-separated molten glass was shaped to obtain a flat glass matrix (34 mm x 65 mm, plate thickness: 0.85 mm).

[0083] Reheat Bending Forming: Heating and Press Forming Using a molding apparatus (GMP-315V, manufactured by Shibaura Machine Co., Ltd.) equipped with a mold and heater, reheat bending forming (heating and press forming) was performed on a glass matrix under the conditions shown in Table 1 below. Afterward, it was slowly cooled to 100°C at 20°C / min, and then the upper and lower molds of the mold were retracted and allowed to cool to room temperature. In this way, a phase-separated glass with a curved surface was obtained. The reheating temperature was below the softening point of the glass matrix. The "viscosity" shown in Table 1 below refers to the viscosity of the glass matrix when it was heated to the reheating temperature and press forming was performed.

[0084] <Example 2> A phase-split glass having a curved surface was obtained in the same manner as in Example 1, except that the reheat molding conditions were changed to the conditions shown in Table 1 below.

[0085] <Example 3> In Example 3, phase-separated glass with a curved surface was obtained without performing reheat molding. More specifically, the phase-separated molten glass was not formed into a flat plate, but was molded into a three-dimensional shape while still in its molten state. Otherwise, phase-separated glass with a curved surface was obtained in the same manner as in Example 1.

[0086] <Phase-Separated Particles> For the obtained phase-separated glass, the average aspect ratio and average major axis of the phase-separated particles were determined in each of the five regions (regions A1 to A5) according to the method described above. The results are shown in Table 1 below.

[0087] <Appearance after post-processing> Post-processing was performed on the obtained phase-splitting glass by grinding a portion of it to expose the cross-section. The exposed cross-section was visually observed to check for the presence or absence of yellowing. If the cross-section was uniformly white and no yellowing occurred at all, it was marked "A" in Table 1 below. If yellowing occurred in the observed area, it was marked "B". "A" is preferred because it has a superior appearance after post-processing.

[0088]

[0089] <Summary of Evaluation Results> As shown in Table 1 above, the phase-splitting glass of Examples 1 and 2 was found to have superior appearance after post-processing compared to the phase-splitting glass of Example 3. In Example 3, since the molten glass was molded into a three-dimensional shape, it is presumed that pressure was applied to the phase-splitting particles, resulting in a larger aspect ratio and an increase in the major axis.

[0090] Furthermore, when the surface roughness (arithmetic mean height Sa) of the first surface having a convex portion was determined for the obtained phase-splitting glass, the relationship was found to be Example 1 < Example 2 < Example 3.

[0091] 1: First surface 2: Second surface 3: Curved surface 3a: Convex surface 3b: Concave surface 4a: Phase-divided particles 4b: Matrix phase 6: Arrow 11: Phase-divided glass 21: Glass base plate 51: Molding mold 52: Upper mold 52a: Molding surface 53: Lower mold 53a: Molding surface 55: Heater A1, A2, A3, A4, A5: Regions

[0092] Furthermore, the entire contents of the specification, claims, drawings, and abstract of Japanese Patent Application No. 2024-219786, filed on December 16, 2024, are incorporated herein by reference as disclosure of the present invention.

Claims

1. A phase-splitting glass having a first surface and a second surface provided opposite to each other, at least one of the first surface and the second surface having a curved portion, and in any of five regions set at equal intervals along the thickness direction in the cross-section of the plate, the average aspect ratio of the phase-splitting particles is 0.600 or more. However, the aspect ratio is the ratio of the minor axis to the major axis of the phase-splitting particles.

2. The phase splitting glass according to claim 1, wherein the difference between the maximum and minimum values ​​of the average aspect ratio is 0.700 or less.

3. A phase-splitting glass having a first surface and a second surface provided opposite to each other, at least one of the first surface and the second surface having a curved portion, and in any of the five regions set at equal intervals along the thickness direction in the cross section in the thickness direction of the plate, the average major axis of the phase-splitting particles is 1,000 μm or less.

4. The phase-splitting glass according to claim 3, wherein the difference between the maximum and minimum values ​​of the average major axis is 0.800 μm or less.

5. The phase-splitting glass according to claim 1 or 3, wherein the average particle diameter of the phase-splitting particles is 0.200 μm or more and 2.000 μm or less.

6. The phase-splitting glass according to claim 1 or 3, wherein the transmittance for light with a wavelength of 300 to 900 nm in a flat plate portion with a thickness of 0.78 mm is less than 1%.

7. The phase-splitting glass according to claim 1 or 3, wherein the whiteness L* value of the first surface is 97 or higher.

8. The phase-splitting glass according to claim 1 or 3, wherein the first surface has a convex portion, the second surface has a concave portion, and the surface roughness of the first surface is less than the surface roughness of the second surface.

9. The phase-splitting glass according to claim 8, wherein the arithmetic mean height Sa of the first surface is 0.7 μm or less.

10. Phase split glass according to claim 1 or 3, wherein the haze is 95% or more.

11. Phase split glass according to claim 1 or 3, wherein the gloss is 96 or more and 110 or less.

12. A method for producing phase-separated glass according to claim 1 or 3, comprising: heating and melting a glass raw material to obtain molten glass; shaping the phase-separated molten glass to obtain a flat glass matrix; and performing reheat molding by heating and press-forming the glass matrix.

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